billc

After more than a year of collecting dust, my Calum daughterboard ECU is now actually IN the car. I drove for a week with the Innovate! AFR as my copilot to assess the fuel mixture and general behavior of the ECU. I am using Calum's SR20DE tune version 4 on my 1991 Classic with AEM CAI, TopSpeed Header and fuel pressure set a 44 psi (with the vacuum hose removed and plugged).

Here is what I have found:

1. The car drives well -- no roughness (after I changed timing from 19*BTDC to 15* BTDC and opened the IAV screw by a quarter turn to restore the idle).
2. The car feels peppier -- pulls nice from mid to high RPM. Can't wait to get it on the dyno.
3. Idle AFR is rich -- 12.5 after full warm up.
4. WOT AFR is rich -- 12.5 on a long pull in 3rd, drifting up toward 12.7 at 7000RPM.
5. Light throttle AFR is rich -- 13.5 at steady speed, light throttle.
6. The car still got 33 MPG in mixed driving even though it is running a little rich.

I do not think that the feedback loop is working to maintain 14.7 at idle and light throttle. Can anyone explain whether the feedback loop has been removed from this tune, or is it just that I have to get the AFR closer to the right value by tuning?

I ran an Active Test with Nissan DataScan with the fuel delivery cut to 90% of what the ECU was trying to deliver. This accomplished the following:

1. Idle AFR increased from 12.5 to 14
2. WOT AFR increase from 12.5 to 13.5-13.7

How should I proceed?

Should I reduce the K value by about 15% to try and adjust the idle mixture to 14.7? This will make other areas of the fuel map too lean and so then I would have to go back and increase individual cells.

OR

Should I reduce the K value (about 7%) to tune in the WOT AFR to 13.3-13.5 and live with the idle?

OR

Some other approach?

Is adjusting K the only way we know to adjust the idle mixture?

Thanks -- I'm new to this stuff, been trying to learn from past posts, so please be gentle.

Bill